•It is the first time that zinc aptamer is used to prepare zinc(II) aptasensor.•SiO2-Pt@meso SiO2 nanoparticles are utilized to fix aptamer and ensure conductivity.•Zinc(II) aptasensor has a very wide detection range from 100 pM to 50 μM.•Zinc(II) aptasensor is applied in zinc detection of ZnB and MCF-7.In this work, bi-functional SiO2-Pt@meso-SiO2 core–shell nanoparticles were designed to prepare a highly sensitive and selective electrochemical zinc(II) aptasesnor. This core–shell structure boasts its SiO2 mesoporous shell and the inside Pt nanoparticles. SiO2 mesoporous shell can fix aptamer without affecting its configuration and can admit electrolyte through the shell. SiO2 core inside can be the substrate of larger amount of Pt nanoparticles that improve the conductivity of the modified electrode dramatically. Due to the application of such a special bi-functional structure and the aptamer's strong combination capacity with Zn2+, Zn2+ is pre-enriched onto the electrode effectively and specifically, so that it can be determined sensitively and selectively. Results have shown that the zinc(II) aptasensor can be utilized at a wide linear working range from 100 pM to 50 μM and a low detection limit of 65 pM, which makes it practical in both biological samples and environment monitoring. This method has been successfully applied in Zn2+ monitoring in human blood and disrupted human cells (MCF-7).